Epoxy resin compositions are well known for a variety of different uses. These uses range from protective coatings and finishes to structural plastic articles.
Most commonly, these compositions are produced in a series of steps. The principal reactants from which they are initially formulated are epichlorohydrin and a polyhydric material--usually a bisphenol A compound. These reactants may be condensed or fused in the presence of a variety of known catalysts, to produce epoxy (or, more specifically, glycidyl ether) compositions.
Many such resin compositions are commercially available. They may be obtained as such or in further combination with conventional curing agents and/or solvents which facilitate application for their individual end uses. Incident to application, these curing agents affect further coupling of the epoxy-ethers to their ultimate, form or use.
Despite long investigation of these epoxy resin compositions and the availablilty of many different ones, certain desired properties have yet to be achieved. In particular, attempts to provide higher solids content compositions for coating and similar uses have heretofore proven unsuccessful.
In the past, epoxy compositions have generally been limited to a maximum resin solids content of about 60% by weight. This was particularly true in, for example, lamination utilities where proper "wet-out" or impregnation of such supports as glass cloth was involved. As a result, application of such compositions has involved treatment for removal of substantial amounts of liquid component--most of which is solvent--from the composition.
More concentrated compositions would, of course, assuage the burden of this final production treatment. They would also allow thicker, individual applications. However, ones having both this and the properties satisfactory for earlier production steps have not been available.